Power capacitors are components in systems for transmission and distribution of electric power for both alternating current and direct current. In power capacitor installations, a plurality of capacitor units is interconnected via series and/or parallel connection in a capacitor bank. Capacitor banks comprise a plurality of capacitor units that may produce noise which can become a problem for the surrounding environment. In order to reduce noise from the capacitor units, partial and/or complete sound attenuation casings or enclosures have been used.
When enclosing capacitor units in sound attenuation enclosures or noise reducing enclosures some noise may pass through openings through which terminal bushings extend. Also, water and moisture can enter into the enclosures, which is undesired.
It is previously known to arrange a sealing element between a terminal bushing and an opening in the sound attenuation enclosure. Terminal bushings comprise sheds which are insulating parts that project from an insulator trunk and are intended to increase the creepage distance in a bushing. By arranging a sealing element in the opening of the sound attenuation enclosure and in abutment with sheds of the terminal bushing, the creepage distance of the terminal bushing is often reduced which is undesired. In order to compensate for the creepage distance loss longer and more expensive cable bushings have therefore been used.
There is a need to reduce noise from capacitor units while at the same time there is a desire to maintain the creepage distance along the terminal bushing as long as possible.